First off, Virgin Radio, even with a bunch of syndicated programs, will not sound different. The English accent is pretty much the same, therefore not much of a difference, and the audience will be more inclined to follow (at least, if they don't, it will be only because it's not original content).

If NRJ decided to start airing shows from the France stations, people will not only change channel because it's not local content, but also because they won't be able to stand the accent.

I don't think the guys at NRJ are that dumb. They'll probably simulcast a concert or award show here and there, but that's pretty much it! French-speaking listeners are much more touchy than they English-speaking counterparts!